Bioinspired Magnetic Janus Core–Shell Micromotors for Delivery of Stem Cells and Vascular Endothelial Growth Factor in Bone Regeneration

Bone defect poses a major challenge for both patients and clinicians. Stem cell therapy based on multifunctional cell delivery microcarriers is a prospective approach for bone repair. However, the realization of efficient and precise stem cell delivery remains to be developed. Here, a bio-inspired magnetic Janus micromotor (MJM) stem cells delivery carrier is proposed for bone repair. The MJM carrier consists of an alginate shell and a solid/aqueous Janus core with different properties for the delivery of stem cells and vascular endothelial growth factor (VEGF). The solid core consists of photopolymerized silk fibroin methacrylate (SFMA) along with magnetic Fe₃O₄@MgSiO₃, which effectively improves the drug release efficiency of VEGF. The aqueous core provides a favorable microenvironment for stem cell proliferation and delivery, which avoids mechanical damage and improves the cell implantation rate. The magnetic Fe₃O₄@MgSiO₃ nanoparticles enable rapid collection of MJM and accurate localization of MJM to the bone defect area with the assistance of a magnet. Based on these features, it is verified that the MJM stem cell microcarriers have favorable angiogenic and osteogenic properties for bone repair. These characteristics indicate that MJM is an effective carrier for stem cell delivery, and is expected to be a viable option for clinically relevant diseases therapy.